1. Field of the Invention
This invention relates generally to a level indicating system, and more particularly to a level indicating system which indicates the maximum peak level of a signal.
2. Description of the Prior Art
In the art, in order to set the recording level of a tape recorder or to determine the input tolerance of a speaker by detecting the maximum output of an amplifier, there has been proposed a peak hold circuit which will hold the maximum value of the peaks of an audio signal in an analog manner. Such a prior art peak hold circuit requires a peak hold capacitor of large capacitance so as to make the discharging time long. For such a peak hold capacitor of large capacitance, it is necessary to use a tantalum capacitor or the like. Further, in order to make the charging time short, a driver stage with an output impedance is required and in order to make the discharging time long it is necessary that the charging voltage for the capacitor be amplified by an FET having a high input impedance.
As a result, such a prior art circuit is complicated in construction as set forth above and not well suited to be made as an integrated circuit. Further, the capacitor can not be charged sufficiently by a short pulse even though the circuit is constructed as above, and hence a peak hold lower than a practical value is attained by the prior art peak hold circuit.